* Using the keyboard: `CTRL-SHIFT-eject`
* Using Alfred: execute the `lock` command
* Using a taskbar icon from Keychain:
* Open the app *Keychain Access*
* Preferences --> Enable the option "Show keychain status in menu bar"
* A lock-shaped icon will appear in the taskbar, with the option "Lock Screen"
* Use Hot Corners:
* *System Preferences* --> Desktop & Screen Saver --> Hot Corners button
* Set one of the corners as "Put Display to Sleep"
* Mouse into the direction of that corner (on the monitor closest to that side, for multi-monitor setups)
* If all else fails, just hold the Power button on your keyboard for a second to put your computer to sleep